Brecknockshire, Wales : Classification : Parish Records

Parish Registers were instigated by Cromwell from 1538, recording every wedding, baptism and burial.
There are gaps in the records for a variety of reasons, such as the civil war, but these records
are a prime source for building family trees. From 1597 a copy of the records had to be made
and sent to the Bishop. Sometimes the Bishops' Transcript may contain more information
than the original, so it can often be worthwhile tracking down both. For more information
on Parish Registers there is a brief history on the Wikipedia Parish Register page.

After 1837 Civil Registration was introduced and the Local BMD and
GRO BMD records become the primary source.

Online book. It explains that start of parish registers and other associated items, such as Phillimore marriages, Hardwicke's marriage act, banns, explanation of register entries, foundlings, as well as some interesting register extracts.